<?php

/* PROJECT INFO --------------------------------------------------------------------------------------------------------
  Version:   1.5.2
  Changelog: http://adaptive-images.com/changelog.txt

  Homepage:  http://adaptive-images.com
  GitHub:    https://github.com/MattWilcox/Adaptive-Images
  Twitter:   @responsiveimg

  LEGAL:
  Adaptive Images by Matt Wilcox is licensed under a Creative Commons Attribution 3.0 Unported License.

  /* CONFIG ----------------------------------------------------------------------------------------------------------- */

include ('includes/application_top.php');

$resolutions = array(1382, 992, 768, 480, 320); // Die Auflösungsschritte für die Bilder erzeugt werden (Bildschirmbreite in Pixel)
$cache_path = DIR_WS_CATALOG . "ai-cache"; // Wo die verkleinerten Bilder gespeichert werden.  Der Ordner muss beschreibbar sein.
$jpg_quality = 80; // Die Qualität der erzeugten JPGs 0 bis 100
$sharpen = TRUE; // Verkleinerte Bilder verlieren an Schärfe, bei TRUE werden die Bilder geschärft 
$watch_cache = TRUE; // stellt sicher das neu hochgeladene Bilder neu verkleinert werden
$browser_cache = 60 * 60 * 24 * 7; // Die Zeit in Sekunden für den BROWSER cache (Standard 7 Tage)
$mobile_first = TRUE; // Ist kein Cookie vorhanden wird zuerst die mobile Version gesendet (wenn FALSE, wird das grösste Bild gesendet)

/* END CONFIG ----------------------------------------------------------------------------------------------------------
  ------------------------ Don't edit anything after this line unless you know what you're doing -------------------------
  --------------------------------------------------------------------------------------------------------------------- */

/* get all of the required data from the HTTP request */
$document_root = $_SERVER['DOCUMENT_ROOT'];
$requested_uri = parse_url(urldecode($_SERVER['REQUEST_URI']), PHP_URL_PATH);
$requested_file = basename($requested_uri);
$source_file = $document_root . $requested_uri;
$resolution = FALSE;

/* Mobile detection 
  NOTE: only used in the event a cookie isn't available. */

function is_mobile() {
    $userAgent = strtolower($_SERVER['HTTP_USER_AGENT']);
    return strpos($userAgent, 'mobile');
}

/* Does the UA string indicate this is a mobile? */
if (!is_mobile()) {
    $is_mobile = FALSE;
} else {
    $is_mobile = TRUE;
}

// does the $cache_path directory exist already?
if (!is_dir("$document_root/$cache_path")) { // no
    if (!mkdir("$document_root/$cache_path", 0755, true)) { // so make it
        if (!is_dir("$document_root/$cache_path")) { // check again to protect against race conditions
            // uh-oh, failed to make that directory
            sendErrorImage("Failed to create cache directory at: $document_root/$cache_path");
        }
    }
}

/* helper function: Send headers and returns an image. */

function sendImage($filename, $browser_cache) {
    $extension = strtolower(pathinfo($filename, PATHINFO_EXTENSION));
    if (in_array($extension, array('png', 'gif', 'jpeg'))) {
        header("Content-Type: image/" . $extension);
    } else {
        header("Content-Type: image/jpeg");
    }
    header("Cache-Control: private, max-age=" . $browser_cache);
    header('Expires: ' . gmdate('D, d M Y H:i:s', time() + $browser_cache) . ' GMT');
    header('Content-Length: ' . filesize($filename));
    header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
    header('Connection: Keep-Alive');
    readfile($filename);
    exit();
}

/* helper function: Create and send an image with an error message. */

function sendErrorImage($message) {
    /* get all of the required data from the HTTP request */
    $document_root = $_SERVER['DOCUMENT_ROOT'];
    $requested_uri = parse_url(urldecode($_SERVER['REQUEST_URI']), PHP_URL_PATH);
    $requested_file = basename($requested_uri);
    $source_file = $document_root . $requested_uri;

    if (!is_mobile()) {
        $is_mobile = "FALSE";
    } else {
        $is_mobile = "TRUE";
    }

    $im = ImageCreateTrueColor(800, 300);
    $text_color = ImageColorAllocate($im, 233, 14, 91);
    $message_color = ImageColorAllocate($im, 91, 112, 233);

    ImageString($im, 5, 5, 5, "Adaptive Images encountered a problem:", $text_color);
    ImageString($im, 3, 5, 25, $message, $message_color);

    ImageString($im, 5, 5, 85, "Potentially useful information:", $text_color);
    ImageString($im, 3, 5, 105, "DOCUMENT ROOT IS: $document_root", $text_color);
    ImageString($im, 3, 5, 125, "REQUESTED URI WAS: $requested_uri", $text_color);
    ImageString($im, 3, 5, 145, "REQUESTED FILE WAS: $requested_file", $text_color);
    ImageString($im, 3, 5, 165, "SOURCE FILE IS: $source_file", $text_color);
    ImageString($im, 3, 5, 185, "DEVICE IS MOBILE? $is_mobile", $text_color);

    header("Cache-Control: no-store");
    header('Expires: ' . gmdate('D, d M Y H:i:s', time() - 1000) . ' GMT');
    header('Content-Type: image/jpeg');
    ImageJpeg($im);
    ImageDestroy($im);
    exit();
}

/* sharpen images function */

function findSharp($intOrig, $intFinal) {
    $intFinal = $intFinal * (750.0 / $intOrig);
    $intA = 52;
    $intB = -0.27810650887573124;
    $intC = .00047337278106508946;
    $intRes = $intA + $intB * $intFinal + $intC * $intFinal * $intFinal;
    return max(round($intRes), 0);
}

/* refreshes the cached image if it's outdated */

function refreshCache($source_file, $cache_file, $resolution) {
    if (file_exists($cache_file)) {
        // not modified
        if (filemtime($cache_file) >= filemtime($source_file)) {
            return $cache_file;
        }

        // modified, clear it
        unlink($cache_file);
    }
    return generateImage($source_file, $cache_file, $resolution);
}

/* generates the given cache file for the given source file with the given resolution */

function generateImage($source_file, $cache_file, $resolution) {
    global $sharpen, $jpg_quality;

    $extension = strtolower(pathinfo($source_file, PATHINFO_EXTENSION));

    // Check the image dimensions
    $dimensions = GetImageSize($source_file);
    $width = $dimensions[0];
    $height = $dimensions[1];

    // Do we need to downscale the image?
    if ($width <= $resolution) { // no, because the width of the source image is already less than the client width
        return $source_file;
    }

    // We need to resize the source image to the width of the resolution breakpoint we're working with
    $ratio = $height / $width;
    $new_width = $resolution;
    $new_height = ceil($new_width * $ratio);
    $dst = ImageCreateTrueColor($new_width, $new_height); // re-sized image

    switch ($extension) {
        case 'png':
            $src = @ImageCreateFromPng($source_file); // original image
            break;
        case 'gif':
            $src = @ImageCreateFromGif($source_file); // original image
            break;
        default:
            $src = @ImageCreateFromJpeg($source_file); // original image
            ImageInterlace($dst, true); // Enable interlancing (progressive JPG, smaller size file)
            break;
    }

    if ($extension == 'png') {
        imagealphablending($dst, false);
        imagesavealpha($dst, true);
        $transparent = imagecolorallocatealpha($dst, 255, 255, 255, 127);
        imagefilledrectangle($dst, 0, 0, $new_width, $new_height, $transparent);
    }

    ImageCopyResampled($dst, $src, 0, 0, 0, 0, $new_width, $new_height, $width, $height); // do the resize in memory
    ImageDestroy($src);

    // sharpen the image?
    // NOTE: requires PHP compiled with the bundled version of GD (see http://php.net/manual/en/function.imageconvolution.php)
    if ($sharpen == TRUE && function_exists('imageconvolution')) {
        $intSharpness = findSharp($width, $new_width);
        $arrMatrix = array(
            array(-1, -2, -1),
            array(-2, $intSharpness + 12, -2),
            array(-1, -2, -1)
        );
        imageconvolution($dst, $arrMatrix, $intSharpness, 0);
    }

    $cache_dir = dirname($cache_file);

    // does the directory exist already?
    if (!is_dir($cache_dir)) {
        if (!mkdir($cache_dir, 0755, true)) {
            // check again if it really doesn't exist to protect against race conditions
            if (!is_dir($cache_dir)) {
                // uh-oh, failed to make that directory
                ImageDestroy($dst);
                sendErrorImage("Failed to create cache directory: $cache_dir");
            }
        }
    }

    if (!is_writable($cache_dir)) {
        sendErrorImage("The cache directory is not writable: $cache_dir");
    }

    // save the new file in the appropriate path, and send a version to the browser
    switch ($extension) {
        case 'png':
            $gotSaved = ImagePng($dst, $cache_file);
            break;
        case 'gif':
            $gotSaved = ImageGif($dst, $cache_file);
            break;
        default:
            $gotSaved = ImageJpeg($dst, $cache_file, $jpg_quality);
            break;
    }
    ImageDestroy($dst);

    if (!$gotSaved && !file_exists($cache_file)) {
        sendErrorImage("Failed to create image: $cache_file");
    }

    return $cache_file;
}

// check if the file exists at all
if (!file_exists($source_file)) {
    header("Status: 404 Not Found");
    exit();
}

/* check that PHP has the GD library available to use for image re-sizing */
if (!extension_loaded('gd')) { // it's not loaded
    if (!function_exists('dl') || !dl('gd.so')) { // and we can't load it either
        // no GD available, so deliver the image straight up
        trigger_error('You must enable the GD extension to make use of Adaptive Images', E_USER_WARNING);
        sendImage($source_file, $browser_cache);
    }
}

/* Check to see if a valid cookie exists */
if (isset($_COOKIE['resolution'])) {
    $cookie_value = $_COOKIE['resolution'];

    // does the cookie look valid? [whole number, comma, potential floating number]
    if (!preg_match("/^[0-9]+[,]*[0-9\.]+$/", "$cookie_value")) { // no it doesn't look valid
        setcookie("resolution", "$cookie_value", time() - 100); // delete the mangled cookie
    } else { // the cookie is valid, do stuff with it
        $cookie_data = explode(",", $_COOKIE['resolution']);
        $client_width = (int) $cookie_data[0]; // the base resolution (CSS pixels)
        $total_width = $client_width;
        $pixel_density = 1; // set a default, used for non-retina style JS snippet
        if (@$cookie_data[1]) { // the device's pixel density factor (physical pixels per CSS pixel)
            $pixel_density = $cookie_data[1];
        }

        rsort($resolutions); // make sure the supplied break-points are in reverse size order
        $resolution = $resolutions[0]; // by default use the largest supported break-point
        // if pixel density is not 1, then we need to be smart about adapting and fitting into the defined breakpoints
        if ($pixel_density != 1) {
            $total_width = $client_width * $pixel_density; // required physical pixel width of the image
            // the required image width is bigger than any existing value in $resolutions
            if ($total_width > $resolutions[0]) {
                // firstly, fit the CSS size into a break point ignoring the multiplier
                foreach ($resolutions as $break_point) { // filter down
                    if ($total_width <= $break_point) {
                        $resolution = $break_point;
                    }
                }
                // now apply the multiplier
                $resolution = $resolution * $pixel_density;
            }
            // the required image fits into the existing breakpoints in $resolutions
            else {
                foreach ($resolutions as $break_point) { // filter down
                    if ($total_width <= $break_point) {
                        $resolution = $break_point;
                    }
                }
            }
        } else { // pixel density is 1, just fit it into one of the breakpoints
            foreach ($resolutions as $break_point) { // filter down
                if ($total_width <= $break_point) {
                    $resolution = $break_point;
                }
            }
        }
    }
}

/* No resolution was found (no cookie or invalid cookie) */
if (!$resolution) {
    // We send the lowest resolution for mobile-first approach, and highest otherwise
    $resolution = $is_mobile ? min($resolutions) : max($resolutions);
}

/* if the requested URL starts with a slash, remove the slash */
if (substr($requested_uri, 0, 1) == "/") {
    $requested_uri = substr($requested_uri, 1);
}

/* whew might the cache file be? */
$cache_file = $document_root . "/$cache_path/$resolution/" . $requested_uri;

/* Use the resolution value as a path variable and check to see if an image of the same name exists at that path */
if (file_exists($cache_file)) { // it exists cached at that size
    if ($watch_cache) { // if cache watching is enabled, compare cache and source modified dates to ensure the cache isn't stale
        $cache_file = refreshCache($source_file, $cache_file, $resolution);
    }

    sendImage($cache_file, $browser_cache);
}

/* It exists as a source file, and it doesn't exist cached - lets make one: */
$file = generateImage($source_file, $cache_file, $resolution);
sendImage($file, $browser_cache);